Method of producing ozonides of unsaturated fatty acids



Oct. 21, 1958 c E. THoRP ErAL 2,857,410"v METHOD oF Paonucmc ozomnss oFUNSATURATED FATTY Acrns iled sept. 28. 1956 METHOD F PRODUCING OZONIDES0F UNSATURATED FATTY ACIDS Application September 28, 1956, Serial No.612,725 20 Claims. (Cl. 260-406) 'Oui-invention `relates to theproduction of ozonides from unsaturated fatty acids and its generalobject is to provide a method for such production which is moreetiicient and economical than the methods which have heretofore beencommercially employed for this purpose.

Anuimportant commercial use of our method is in the production fromoleic acid of oleic ozonides from which azelaic and pelargonic acids maybe derived. However, theinvention may also be used for the formation oforganic oxonides from fatty acids in general. Thus, it can be applied tothe production of such ozonides from naturally-'occurring fatty acids offrom 10 vto 24 carbons chain. length derived from natural fats, oils andwaxes, orl from Vderivatives and compounds of these acids, such astheiresters, nitriles, etc.

An important object of the invention is to provide such a method inwhich the unsaturated fatty acids, or their derivativesor compounds, andozone are reacted in vapor phase and at subatmospheric pressure. In thismanner improved efliciency and greater yields of organic ozonidesareobtaiued, as compared with the methods heretofore used.

Another of our objects is to provide a method for the 'purpose abovestated in which no catalysts are required to promote the reaction.

Av further object of the invention is to provide a method of thischaracter in which the ozone needed for the reaction is utilizedmorefully than in other methods used for'the production of such ozonides.

A still further object of the invention is` to provide a method for thepurpose stated in which the ozonizer, which is used to produce the ozoneused in the reaction, may Vbe so integrated with the other apparatusemployed that less structure and fewer processing steps are necessaryythan in other comparable processes, thus lowering the capitalinvestment required and the cost of operation in the practice of themethod.

While not necessarily limited thereto, the invention has an importantcommercial use in increasing the nancial return to packing plants fromtallow, which is one of their major by-p'roducts. Tallow is a goodsource of oleic acid, which, however, often is so plentiful that itsmarket price is too low to permit its marketing, as such, at much, ifany, profit. Therefore, in many cases a better return can be obtained byconverting the oleic acid into azelaic and pelargonic acids whichnormally command suiciently high prices to produce a better profit tothe packer than if the oleic acid were sold as an end product. Thus, byimproving eiciency and lowering the cost of producing ozonides of theoleic acid from which the azelaic and pelargonic acids are derived, ourinvention is potentially of very substantial value to the packingindustry.

The above and other objects and advantages of the invention will beapparent from the following description thereof, taken in connectionwith the accompanying block diagram and flow sheet illustrating thesteps of our meth- United States Patent O od and, in general, the unitsof an apparatus by which it may be practiced.

As thus illustrated, the method of our invention may` operation thereof,someA means must be provided for cooling the ozonizer. Also, inaccordancewith our invention, the oleic acid must be heated, in theabsence of oxygen and under reduced pressure, so as to keep it fromboiling and thus degrading and so that it will vaporize when introducedinto a vapor phase reactor. Thus, the arrangement shown allows these`two necessary functions to complement each other, by having the oleicacid directed through the coil 11 to cool the ozonizer 12 and at thesame time to be heated by the ozonizer prior to its introduction into avapor phase reactor 13. If the heat transferred to the oleic acid as itis conducted through the coil 11 is not great enough to raise itstemperature to the point desired, additional heating means (not shown)may be` provided in the circuit.

-We prefer to use commercial oxygen of a purity of approximately 99.5%in our process. While air contains a suicient amount of oxygen to beozonized, a much larger and more intricate ozonizer would be needed ifthe oxygen were derived from this source, and it is accordingly moreeconomical to use commercial oxygen and a smaller ozonizer than tousefair and a more costly ozonizer. The oxygen is contained in a tank 14from which itis conducted `to theV ozonizer 12.

The ozonizers in common use create ozone by electronic discharge. It isnow known that the production of ozone by electronic discharge ispreceded by the formation of activated oxygen which, in the atomicstate, has a life of only a few milliseconds. However, by virtue of theease with which the apparatus necessary to practice this method may beintegrated, it is possible to couple the ozonizer 12 closely enough tothe vapor phase reactor 13 to utilize such of this short-lived activatedoxygen as is formed in the ozonizer as well as that which is produced bydecomposition of ozone in the reactor.

The ozone and the heated oleic acid are introduced simultaneously andcontinuously into the vapor phase reactor 13. The amounts of oleic acidand ozone are met# ered, so that a proper amount of each is, introducedinto the heated reactor.

The heated oleic acid, upon being introduced into said reactor, iscaused to vaporize by the reduced pressure in the presence of ozone andactivated oxygen, the reaction causing the formation of fog or smokewhich contains a portion of the reacted oleic acid.. The exact mechanismof the ozonization is not thoroughly established; however,

it has been proved in practice that the condensate collected from thereaction and certain paricles in the fog or smoke formed thereby formoleic ozonides from which azelaic and pelargonic acid may be derived.

In terms of Weight, the ratio of oleic acid to ozone introduced into thereactor 13 theoretically could be as low as 5.88 to l, since onemolecule of oleic acid is 5.88 times as heavy as a molecule of ozone.However, any amount of oleic acid can be introduced into the reactor 13,so long as the ratio is 5.88 to 1 or greater, and complete ozoneutilization will occur, since the additional acid acts as a diluent, andthe azelaic yields from the resultant ozonides are not affected by theadditional oleic acid. Complete utilization of the ozone isindicated bythe fact that the effluent gas removed from the reactor 13 does PatentedOct. 2l, 1,958

not liberate iodine from a potassium iodide solution. In practice it hasbeen found preferable to introduce a greater amount of oleic acid intothe reactor 13 than will be actually used, since-f thei excess oleicacid which will remain unreacted in the reactor 13. actsv to .dilute theozonides formed, decreasing their viscosity and making themeasiertotransport.

The pressure maintained in the vapor phasereactor 13 will', of course,determinetheV temperature to which the oleicacid must be heatedy beforeintroduction thereinto. The vapor pressure of oleic acid at a giventemperature is known to those skilled in the art and, once the pressurein the` reactor is determined, it is a simple matter to determine thetemperature to which the. oleicacid must be' heated in order that itwill vaporize when introduced therein.

Thus it is known that the vapor pressure of oleic acid varies from thatequal to l millimeter of mercury, when the temperature thereof is 176.5C., to that equal to 760 millimeters of mercury when the temperaturethereof is 360 C.- Since a pressure of 760 millimeters of mercuryconstitutes atmospheric pressure, any reaction of oleic acid and ozoneunder a pressure in excess of that would constitute a spray reaction,rather than a vapor phase reaction.

By experimentation it has been found that when practicing lour inventionextremely low pressures,` i. e. those equal to millimeters of mercury orless, are notY desirable. This is because some -diiculty is involved inmaintaining them and the costY of theV apparatus which would be requiredto-maintainsuch low pressure is disproportionate tothe cost ofthatapparatus necessary for maintaining more moderate pressures. Thereaction temperature corresponding to a pressure of 10 mm. of mercurywould be 223 C.

It has also been found tained in the Vapor phase reactor 13 approachesatmospheric, great danger of explosion arises. Also, since the pressurein thel reactor Vis a corollaryA of the temperature to which the loleicacid must be'heated, itis desirable to maintain that pressurev in thereactor which will allow the oleic acid to lvaporizey therein withoutthe necessityr of such4 oleic acid being heated to that point at whichit begins to degrade.Y Since oleic acid tends'to degrade to some extentat temperatures in excess of 300 C., the pressure maintained within thevapor phase reactor 13 should preferably not exceed the vapor pressureof oleic acid at such temperature, which .is equal to 150 mm. of

mercury. s

The data hereinbelow set forth were derived from tests conducted usingour method for the vapor phase reaction of oleic acid with ozone. Eachof such tests was conducted with the pressure in the vapor phase reactor13 and the temperature to which the oleic acid was heated prior to itsintroduction thereto varying from each of the other tests.

Oper- Theoretie Actual Percent Total Operating ating Yield' Yield Yieldof Ozone Pressure Temper- Azelaic Azelaic Theoreti- (Grarus) (mm. Hg)ature Acid 1 Acid cal C.) (Grams) (Grams) 1 The theoretical yieldsexpressed above are based upon the following formula,` which describesthe'theoretical yield from reacting oleic acid and ozone; 5.88 unitsoleic acid plus l unitrozone equals 3.91 units azelaic acid plus 3.29units pelargonic acid. The lunits in such formula mean units otnwetght,since as hereinbefore, described one molecule of oleic acid weighs 5.88times as much as one unit of ozone.

As the oleic acid and ozone and activated oxygen are introduced'into thereactor'13, a condensate and smoke are formed,` as previously stated.The condensate is collected in a condenser 19 and the smoke resultingfrom that, when therpressure main-- the reaction of the oleic acid andozone, which `contains particles of reacted oleic acid, 'is also coursedthrough the condenser 19 where the reacted'oleic acid is removedtherefrom. A suitable device such as a Vacuum pump 15 l, draws the smokethrough the condenser and maintains the reduced pressure in the vaporphase reactor 13.

The -eiiiuent gases removed from the 'condenser 19 by the vacuum pump 15are then directed to a heat exchanger 16 which removes heat therefrom.Since such gases contain a` good deal of oxygen which itis desir-Y` ableto recycle, it is necessary to cool such gases'before theirre-introduction into the ozonizer 12. Upon leaving the heat exchanger16, the gas is conducted to a gas scrubber 17 wherein organic vapor andorganic particles contained in the oxygen are removed. Such re-condi-`tioned oxygen is then coursed to a gas dryer 18 where the nal operationof cleaning the oxygen takes place t by removingA therefrom the watervapor contained in' such oxygen.V Such reconditioned` oxygen is thentransferredlto the tank 14.V

The ozonides -collected .in the condenser 19are1trans-l ferred toaiwater extractor 20 whereinhotwater from'a` water supply tank 21 ismixed therewith, hydrolizing'the ozonides and forming azelaicV andpelargonic acid.

The hydrolized ozonides extractor 20 to a separator the unreacted oleicacid,.neither of ywhich is ywater solu-V ble.. Theazelaic acid containedin a water solutionis directed from the separator. 22 to an evaporatorv23. which causes thewater to vbei evaporated, leaving a crystalline`form of azelaic acid, which is drawnoff from .the e'vapo-f rator 23 to acontainer.

The unreactedgolec acidcand the pelargonic acid. are conducted to astill 24. The atmosphere in the still 24 is maintained atsub-atmospheric pressure bythe vacuum p pump 15.

is accomplished therein, at atmospheric pressures would cause the-oleic;acid to degrade'.` The fractional distillationV occurringiine such'still 24 separates the oleic acid from. the .pelargonicac id. The oleicacid Vresultingfrom such. fractional distillation g 10, andthepelargonic` is-recycled to theV oleic acid tank l acid-producedthereby is'directed-.to a suitablelreceptaclef;

Since. certain changes -1 can be made inithey foregoing!` proceduresWithoutl departing from the spiritfand scope of the invention', itlis'intendedl thatv all description ofsuchi procedures seti forthhereinbefore' shall be interpretedas` illustrative andnotfin alimitingsense.

We claim:

l. A method-V of producing ozonides of unsaturated. Y fatty acids byreactingsuch acidsinfthe vaporphase` that equal.

with ozone, at a pressure in the range between to 1 mm. of mercury andthat equal to 760mm. of mer cury and at a correspondingtemperaturein therange-bef;V t

tween l76.5 Cfand 360 C.

2. Avmethod of producing ozonides `of unsaturated? ture in the rangebetween 176.5 and 360 C.

3. A method of producing ozonides `of unsaturated4 fatty acids byreacting such acids in the vapo'rphasewith"` ozone at subatmosp'hericpressure and ata temperature` not exceeding 360 C.

4. A method ofv producing ozonides` of unsaturated fatty acids byreacting such acids in the vapor phase with'A ozone and activated oxygenat subatmospheric pressure and at a temperature not exceeding 360 C.

5. A method of producing ozonides of oleic acid ,by ref.

acting oleic acid in the vapor phase with ozone in thel ratio of atleast5.88 to l at subatmosphericpressure and at a temperature not exceeding360 C.

are conducted from the waterl 22 in which the water soluble i azelaicacid is separated from the pelargonic acid and` It is necessary tomaintain sub-atmospheric: pressure in the still 24 since fractionaldistillationt.which;` of the oleic and pelargomc acid` 6. A method ofproducing ozonides of oleic acid by reacting oleic acid and ozone in thevapor phase in an area in which the pressure is maintained between anabsolute pressure equal to one millimeter of mercury and an absolutepressure equal to 150 millimeters of mercury and in which acorresponding temperature between 176.5 C. and 300 C. is maintained.

7. A method of producing ozonides of unsaturated fatty acids of from to24 carbons in chain length by reacting such acids and ozone in the vaporphase in an area in which the pressure is maintained between an absolutepressure equal to one millimeter of mercury and an absolute pressureequal to 150 millimeters of mercury.

8. A method of producing ozonides of oleic acid by reacting oleic acidwith ozone and activated oxygen in the vapor phase, such reaction beingproduced by heating oleic acid to the temperature necessary to cause itto subsequently vaporize in the presence of ozone and activated oxygenand then introducing the same and said ozone and activated oxygen intoan area of subatmospheric pressure.

9. A method of producing ozonides of unsaturated fatty acids of from l0to 24 carbons in chain length by reacting such acids in the vapor phasewith ozone and activated oxygen, said reaction being produced by heatingsuch acids to the temperature necessary to cause them to subsequentlyvaporize in the presence of ozone and activated oxygen and thenintroducing the same and said ozone and activated oxygen into an area ofsubatmospheric pressure.

10. A method of producing ozonides of unsaturated fatty acids byreacting such acids and ozone in the vapor phase in an area in which theabsolute pressure is between one millimeter of mercury and 150millimeters of mercury and the temperature of such acids is between176.5 and 300 C., depending on the amount of such pressure.

11. A method of producing ozonides of oleic acid by reacting oleic acidin the vapor phase, at subatmospheric pressure and at a temperature notexceeding 360 C., with a gas comprising ozone and activated oxygen, inwhich the concentration of ozone is between 1% and 3% by weight.

12. A method of producing ozonides of unsaturated fatty acids of from 10to 24 carbons in chain length by reacting such acids in the vapor phase,at subatmospheric pressure and at a temperature not exceeding 360 C.,with a gas comprising ozone and activated oxygen, in which theconcentration of ozone is between 1% and 3% by weight.

13. A method of producing ozonides of unsaturated fatty acids byreacting such acids in the vapor phase with ozone and activated oxygenat a pressure in the range between that equal to 1 mm. of mercury andthat equal to 760 mm. of mercury and at a corresponding temperature inthe range between 176.5 C. and 360 C., condensing the gases resultingfrom such reaction and recycling the oxygen contained in such gases.

14. A method of producing ozonides of unsaturated fatty acids byreacting such acids in the vapor phase with ozone and activated oxygenat a pressure in the range between that equal to 1 mm. of mercury andthat equal to 760 mm. of mercury and at a corresponding temperature inthe range between 176.5 and 360 C., condensing the gases resulting fromsuch reaction and recycling the oxygen contained in such gases, the samebeing cooled, scrubbed and dried during such recychng.

15. A method of producing oleic ozonides by reacting oleic acid in thevapor phase with ozone and activated oxygen at a pressure in the rangebetween that equal to 1 mm. of mercury and that equal to 760 mm. and ata corresponding temperature in the range between 176.5 C. and 360 C.,condensing the gases resulting from said such reaction, recycling theoxygen contained in such gases and hydrolyzing the ozonides contained inthe condensate to form a solution from which both azelaic acid andpelargonic acid are derived.

16. A method of producing oleic ozonides by reacting i oleic acid in thevapor phase with ozone and activated oxygen at a pressure in the rangebetween that equal to 1 mm. of mercury and that equal to 760 mm. and ata corresponding temperature in the range between 176.5 C. and 360 C.,condensing the gases resulting from said such reaction, recycling theoxygen contained in such gases, hydrolizing the ozonides :contained inthe condensate to form a solution from which both azelaic acid andpelargonic acid are derived, and recycling the unreacted oleic acid.

17. A method of producing oleic ozonides by reacting oleic acidin thevapor phase with ozone at a pressure in the range between that equal to1 mm. of mercury and that equal to 760 mm. and at a correspondingtemperature in the range between 176.5 C. and 360 C., condensing thegases resulting from said such reaction, hydrolizing the ozonidescontained in the condensate to form a solution from which both azelaicacid and pelargonic acid are derived, and recycling the unreacted olei-cacid.

18. A method of producing oleic ozonides by reacting oleic acid in thevapor phase with ozone in at least the ratio of 5.88 units to 1 unit ata pressure in the range between that equal to about 10 mm. of mercuryand about mm. of mercury and at a corresponding temperature in the rangebetween about 223 C. and about 300 C.

19. A method of producing ozonides of oleic acid by reacting oleic acidwith ozone in the vapor phase, such reaction being produced by heatingoleic acid to the temperature necessary to cause it to subsequentlyvaporize in the presence of ozone and then introducing the same and saidozone into an area of subatmospheric pressure.

20. A method of producing ozonides of unsaturated fatty acids of from 10to 24 carbons in chain length by reacting such acids in the vapor phasewith ozone, said reaction being produced by heating such acids to thetemperature necessary to cause them to subsequently vaporize in thepresence of ozone and then introducing the same and said ozone into anarea of subatmospheric pressure.

References Cited in the le of this patent FOREIGN PATENTS Germany Mar.20, 1931 Austraha Sept. 22, 1955

1. A METHOD OF PRODUCING OZONIDES OF UNSATURATED FATTY ACIDS BY REACTINGSUCH ACIDS IN THE VAPOR PHASE WITH OZONE, AT A PRESSURE IN THE RANGEBETWEEN THAT EQUAL TO 1MM. OF MERCURY AND THAT EQUAL TO 760MM. OFMERCURY AND AT A CORRESPONDING TEMPERATURE IN THE RANGE BETWEEN 176.5*C.AND 360*C.